Sunday 29 April 2018

Western Australian beach closed after two women stung by Irukandji Jellyfish.

Cable Beach in Broome, Western Australia, has been closed the public after two swimmers were stung by Irukandji Jellyfish, Carukia barnesi, this week. Both swimmers are described as female, but neither has been named. The first was stung on Wednesday 25 April 2018, prompting a 24 hour closure of the beach, the second on Sunday 29 April, leading to the beach being closed off again, potentially for a longer period. Both women are being treated in a local hospital, where their condition is described as 'stable'.

An Irukandji Jellyfish, Carukia barnesi. University of California Museum of Paleontology.

The Irukandji Jellyfish is a form of Box Jellyfish, Cubozoa, found along the northern coast of Australia, which has both a particularly potent sting and a very small size, making it particularly dangerous to swimmers. The Jellyfish are typically about 5 mm across, though they can reach as much as 30 mm, with tentacles between 5 and 50 mm in length. The sting of these Jellyfish is particularly potent, and can cause muscle aches, back pain, nausea, headaches, chest and abdominal pains, sweating, high blood pressure, difficulty breathing, and in extreme cases death.

 The location of Cable Beach, where two women were stung by Irukandji Jellyfish this week. Google Maps.

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Tchadailurus adei: A new species of Sabre-toothed Cat from the Miocene of Chad.

Carnivorans play a major role in most Mammalian faunas, modifying the behaviour of almost all other Mammal species, and providing a major source of selective pressure. The faunas of Miocene Africa were dominated by Mammals, but only six Miocene African fossil sites preserve fossil Carnivorans, the Sahabi deposits of Libya, the Nawata and Lothagam formations of Kenya, the Middle-Awash deposits of Ethiopia, the Langebaanweg cave fauna of South Africa and the Toros Menalla Site in the Djourab Desert of Chad. The Toros Menalla Site is most noted for the hominid Sahelanthropus tchadensis, but has also produced a wide range of other Mammal fossils, including a range of Carnivorans that includes Mustelids (Weasels etc.), Canids (Dogs), Herpestid (Mongooses), Viverrids (Civets), Hyaenids (Hyenas) and Felids (Cats).

In a paper published in the journal Geodiversitas on 15 February 2018, Louis de Bonis of the Université de Poitiers, Stéphane Peigné of the Département Origines et Évolution at the Muséum national d’Histoire naturelle, Hassane Taisso Mackaye and Andossa Likius of the Département de paléontologie at the Université de N’Djamena, and Patrick Vignaud and Michel Brunet also of the Université de Poitiers, describe a new species of Sabre-toothed Cat, Machairodontinae, from the Miocene Toros Menalla Site in Chad.

The new species is named Tchadailurus adei, where 'Tchadailurus' means 'Chad Cat' in Greek and 'adei' is 'small' in Goran (a local language). The species is described from a single disarticulated partial skeleton, comprising some isolated teeth and jaw elements, fragments of other parts of the jaws and skull, some isolated vertebrae and ribs, and portions of all four limbs. It is smaller than other Sabre-toothed Cats known from the site, about the size of a modern Lynx, and has a distinctive double-keeled canine tooth.

Tchadailurus adei, from Toros Menalla. Left maxilla with C-M1 in labial (A1), lingual (A2), and occlusal (A3) views; right hemimandible with c-m1 in lingual (B1), labial (B2), and occlusal (B3) views; fragmentary atlas in dorsal (D1) and ventral (D2) views. Scale bar is 10 mm. De Bonis et al. (2018).

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Asteroid 2018 HV passes the Earth.

Asteroid 2018 HV passed by the Earth at a distance of about 154 800 km (0.40 times the average  distance between the Earth and the Moon, or 0.10% of the distance between the Earth and the Sun), slightly after 5.05 pm GMT on Sunday 22 April 2018. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2018 HV has an estimated equivalent diameter of 3-9 m (i.e. it is estimated that a spherical object with the same volume would be 3-9 m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere between 50 and 33 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2018 HV. Minor Planet Center.

2018 HM was discovered on 21 April 2018 (the day before its closest approach to the Earth) by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2018 HV implies that the asteroid was the 21st object (object V) discovered in the second half of April 2018 (period 2018 H).   

2018 HV has a 514 day orbital period and an eccentric orbit tilted at an angle of 10.3° to the plane of the Solar System, which takes it from 0.65 AU from the Sun (i.e. 65% of he average distance at which the Earth orbits the Sun, slightly inside the orbit of the planet Venus) to 1.86 AU from the Sun (i.e. 186% of the average distance at which the Earth orbits the Sun, and more distant from the Sun as the planet Mars). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer). This means that close encounters between the asteroid and Earth are common, with the last having occurred in October 2015 and the next predicted in April 2022. 2018 also has occasional close encounters with the planet Venus, with the last having occurred in December 2009 and the next predicted for April 2021.

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Explosion at illegal oil well kills 21 in Aceh Province, Sumatra.

Twenty one people have died and another 42 people have been injured following an explosion at an illegal oil well in the village of Pasir Putih in Aceh Province, Sumatra, on Wednesday 25 April 2018. The well was apparently run by local people from the village, which lies within an area where all legal drilling is controlled by the Indonesian state oil company Pertamina. The operators had apparently drilled own to a depth of about 250 m, when they struck a pocket of pressurised oil which they were unable to control and sprayed freely from the well. This attracted the attention of other people in the village, who gathered to try to collect some of the oil. At some point after this the oil was ignited, causing a major explosion and fire, though accounts of how this happened vary (though there would seem to have been a degree of bad luck involved, as crude oil is not usually easy to ignite).

Flames issuing from an illegal oil well in Passir Putih Village, Aceh Province, on 25 April 2018. Maulana/Antara Foto/Reuters.

The fire destroyed at least five homes and burned for several hours, before eventually being extinguished by teams from the National Disaster Mitigation Agency assisted by specialist fire fighting crews loaned by Pertamina. Authorities in the area are concerned there may still be undiscovered casualties in the village, and are planning to prosecute those responsible for the disaster.

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Steamboat Geyser in Yellowstone National Park, erupts three times in six weeks.

The Steamboat Geyser in the Yellowstone National Park, Wyoming, erupted on Friday 27 April 2018, the third such eruption this year, following events on 19 April and 15 March. This is the first time the geyser has erupted since September 2014, and the first time it has erupted three times within a year since 2003. This has led to some speculation that these events may indicate a forthcoming eruption on the Yellowstone Supervolcano (a popular idea with some elements of the media), but no such inference can be made, with scientists at the Yellowstone Volcano Observatory pointing out that these eruptions have been considerably smaller than the largest known events at the Geyser, which cab produce water spouts reaching over 90 m in the air and lasting for up to 40 minutes.

Eruption on the Steamboat Geyser on 27 April 2018. Yellowstone National Park/Twitter.

The Yellowstone National Park lies on top of the caldera of an active volcano. The geysers and hot springs are fuelled by water from the surface peculating through the ground until it encounters hot rocks or magma, which heats it rapidly. This hot water then rises back to the surface to fuel the geysers and fill the volcanic pools of the park. As it passes through the rocks the water absorbs chemicals from the surrounding minerals, with water with different mineral properties in different parts of the park, creating a variety of brightly coloured pools.

  Yellowstone is home to one of the world’s largest active volcanic systems. Cataclysmic eruptions in the past few million years created huge volcanic depressions called “calderas.” The youngest, the Yellowstone Caldera, was formed 640 000 years ago. Since then, about 80 eruptions of rhyolite (thick, sticky lava) and basalt (more-fluid lava) have occurred. The caldera’s interior is largely covered by rhyolites, most erupted in the past 160 000 years. Large hydrothermal (steam)-explosion craters formed in the past 14 000 years are located near Yellowstone Lake and in major geyser basins. Recent earthquakes (1973 to 2002) were concentrated between Hebgen Lake and the Norris Geyser Basin and along faults. USGS.

The Steamboat Geyser is the world's second largest, after the Waimangu Geyser in New Zealand, which erupts even less frequently (it last erupted in 1908), and even small eruptions like those seen this year are much larger than those seen on the nearby Old Faithful Geyser, which erupts sever times a day with water reaching 30-40 m above the ground. The size of a water spout related to how much water pressure (caused by water expanding as it is heated and some of it turns to vapour) builds up before there is a release. Therefore the more frequent, smaller, eruptions seen this year are a symptom of water escaping at a lower pressure, rather than a symptom of increasing volcanic activity within the caldera.

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Saturday 28 April 2018

Magnitude 4.1 Earthquake in San José Province, Costa RIca.

The United States Geological Survey recorded a Magnitude 4.1 Earthquake at a depth of 29.3 km, roughly 15 km to the northwest of the city of San Isidro de El General in San José Province, Costa Rica, slightly after 9.30 am local time (slightly after 3.30 pm GMT) on Friday 27 April 2018. There are no reports of any damage or casualties associated with this event, but it was felt across much of central Costa Rica.
The approximate location of the 27 April 2018 San José Earthquake. USGS.
Costa Rica lies on the southern margin of the Caribbean Plate; to the south of the country the Cocos Plate, which underlies part of the eastern Pacific Ocean) is being subducted under the Middle American Trench, passing under Central America as it sinks into the Earth's interior. This is not a smooth process, and the plates often stick together until the pressure builds up enough to force them to shift suddenly, causing Earthquakes. As the Cocos Plate sinks deeper if is partially melted by the friction and the heat of the Earth's interior. Some of the melted material then rises up through the overlying Caribbean Plate, fuelling the volcanoes of Central America.
Diagram showing the passage of the Cocos Plate beneath Costa Rica (not to scale). Carleton College.
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.
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Cotesia nuellorum: A new species of Braconid Wasp from Texas.

Braconid Wasps are small parasitoid wasps (Wasps whose larvae grow inside the bodies of a living animal host) targeting a variety of Insect and Spider species. They are unusual in that they will lay multiple eggs within the same host (most parasitoid Wasps lay a single egg on each host), thereby allowing multiple larvae to mature within a large host, which is not necessarily killed in the process. Braconid Wasps are often fearsome in appearance, but are harmless, other than to targeted host species, as they lack stings. Members of the genus Cotesia target large Butterfly and Moth caterpillars, including many species considered to be significant agricultural pests, making them of considerable interest to entomologists.

In a paper published in the journal ZooKeys on 5 February 2018, James Whitfield of the Department of Entomology at the University of Illinois, Urbana, and Robert Nuelle Jr. and Robert Nuelle III, of the Sam Houston State Natural History Collections Huntsville, describe a new species of Cotesia from Texas.

The new species is named Cotesia nuellorum, in honour of Robert Nuelle Jr. and Robert Nuelle III, who discovered the first examples of the species, raised from an infected Hickory Horned Devil caterpillar, Citheronia regalis, found in the Sam Houston National Forest in Walker County, Texas, and subsequently from an infected Luna Moth, Actias luna, from the same location. 

Larva of Citheronia regalis with emerged larvae and cocoons of Cotesia nuellorum, in rearing container. Robert Nuelle Jr. in Whitfield et al. (2018).

The adult Wasps reach 2.0-2.2 mm in length, with males slightly smaller than the females, and are black in colour with dark brown markings and brown legs. The species was found in an area of managed woodland in Texas, but is likely to be more widely distributed, as both known host species are widespread in North America and known to be prone to Braconid infections across their range.

Cotesia nuellorum, adult female in lateral view. Whitfield et al. (2018).

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